I'm also into this crypto market and prices are very unpredictable. So what I do is I buy and sell regularly but never sell at a loss means I buy monthly or weekly in small quantities whenever I get some extra money and sell some portion of it when I make around 20 to 30% profit and wait for some more time.
Luckily I didn't buy any bitcoins above 15K because I was worried that prices went up super fast and waiting for it to correct but it has corrected too much now. I too have some coins which bought above 10K but I believe prices will again go up so I will just wait.
Yep, very smart move. Honestly it's the same with a majority of investment, but please make sure you realize that Bitcoin is not an "investment" of a certain company, but rather an asset/currency that you are the only person who is responsible for in terms of it's corresponding private key.
As for me personally, I like to make routine "investments" into whatever I feel is better at the time and hold until green no matter what. Whatever you invest consider that money gone, period. So for me as an example, I throw in money into crypto at times when I feel the crypto market is feeling bullish, and then I throw in money into stocks when I feel the stock markets are bullish, etc.
Only sell when you are sure about the mid to long term outcomes look dire.